Small windpower systems are identified as systems intended to produce clean wind-based energy on a limited basis for single or low numbers of closely situated buildings or electrically operated devices. A schematic of a typical prior art small windpower system 10 is illustrated in FIG. 1. The prior art system includes a wind turbine 12 pivotably mounted on top of a pole. The pivoting connection allows the turbine to turn and orient itself relative to the actual wind direction. The wind turbine is mechanically connected to a generator (not shown) that incorporates a rotor structure, which is powered by the transmission of mechanical energy from the turbine, and a stator structure that generate electrical current through the use of magnets and armature coils in a known manner.
As current is generated, it passes to a charge regulator 14. The charge regulator is necessary to regulate the current, voltage, and frequency, all of which vary due, in part, to the inconsistent rotational speed of the wind turbine. Regulation is necessary to make the energy generated by the system compatible with public utilities and modern electronic devices. From the charge regulator, energy is passed to a battery or bank of batteries 16 for storage. Because the current generated by the system is DC, an inverter 18 must be used to convert the current to AC for common use before it passes to an electrically powered device 20.
While these prior art systems do provide clean energy, they suffer from a number of significant drawbacks. First, the typical propeller-type turbines used require “clean air” for efficient operation. Turbulent air greatly reduces the performance of these turbines. In order to maximize the “clean air” available to the turbine, these systems are typically installed at least 25 feet above any surrounding object and preferably with no objects within 500 feet in any direction. Thus, the practical footprint required for these systems is actually fairly large, making them impractical for urban areas for at least this reason. Further, the typical wind speed required to produce the necessary lift along the turbine blades for start up of these turbines is approximately 8 mph. Also, the blades are prone to failure in winds of speeds as low as 28 mph. Failure of the turbine blades can create substantial property damage and potential personal injury, which is yet another reason that these systems are not suitable for urban applications. Additionally, these turbines create significant amounts of noise, due to the pulsing of air as the blades pass in front of the required post or tower structure and “white noise” from the tip vortices at the ends of the blades, and have a very significant visual profile.
The prior art systems also require multiple mechanical connections to transfer the rotational energy of the turbine to the generator rotor, resulting in significant inefficiencies. In some cases, these systems suffer as much as a 30% loss of potential energy between the turbine and the generator. Furthermore, the multiple electrical components required to condition the generated energy also contribute to losses in the system in the form of heat. In some systems, these inefficiencies result in an additional loss of up to 30% of potential energy.
Therefore, it would be desirable to provide a more efficient wind or fluid-driven energy generation system that required fewer components and a lower start-up wind speed and was suitable for use in urban applications due to reduced noise and visual impact.
The present invention is directed to meeting one or more of the above-stated desirable objectives.